1. Field of the Invention
The present invention relates to a portable telephone apparatus of mobile communication type, in particular, to a portable telephone apparatus with a security function for preventing power from being supplied in the event that the apparatus has been stolen.
2. Description of the Related Art
Conventionally, when a portable telephone unit has been mislaid or stolen, it can be freely used by a person who found or stole it unless the owner asks the operator company for the to invalidate the telephone unit. To prevent such a problem, a dial-lock function has been used. The dial-lock function serves to prevent a person other than the owner of the portable telephone unit to make a call. As a related art reference of the dial-lock function, Japanese Patent Examined Publication 64-3414 entitled "Dial-lock Apparatus for Car Telephone unit" has been disclosed. With the dial-lock apparatus according to the related art reference, when the user performs a simple switch operation, the telephone unit enters a dial-lock state in which he or she can receive a call, but can not make a call. The dial-lock state cannot be canceled unless the user enters a predetermined password. When the battery of the telephone unit is dismounted and then mounted, the telephone unit enters the dial-lock state again. Thus, even if the telephone unit is stolen, it can be prevented from being freely used.
In Japanese Patent Laid-Open Publication No. 4-271646, another related art reference has been disclosed. In this related art reference, identification information has been assigned to a pair of a battery charger and a cordless telephone main unit. When another cordless telephone unit is mounted on a particular battery charger, an alarm is generated. When a cordless telephone unit is used, if it does not have a parent-child relation with the particular telephone main unit, the cordless telephone unit is prohibited from being used. However, in this related art reference, the technology by which identification information is assigned to a battery has not been disclosed.
However, a first problem with the above-described related art references is that the user of a portable telephone unit does not always use the dial-lock function.
In other words, to make a call, the user of the portable telephone unit should deactivate the dial-lock function. In addition, after the user has completed the call, he or she sometimes forgets to reactivate the dial-lock function.
A second problem with the above-described related art reference is that the user tends not to use the dial-lock function.
In other words, unless the user carefully reads the manual of the portable telephone unit, he or she does not know how to use the dial-lock function.
A third problem with the related art references is that if the portable telephone unit is stolen in the state in which the dial-lock function has not been turned on, the owner must ask the operator company to invalidate of the registered ID number of the stolen portable telephone unit to prevent the stolen units from being.
In other words, if the portable telephone unit has been stolen and the user is not aware that it was stolen, the thief can freely use it.